1. Field of the Invention
The present invention relates to a digital camera that controls the emission amount of a flash using face information included in a subject, and a method therefor.
2. Description of the Related Art
Generally, digital cameras initiate image taking before the shutter release button is depressed, and the exposure and focus adjustments are performed using the image obtained during that period. The image obtained during that period is also used for a flash adjustment to obtain an adequate emission amount of a flash. In the past, the method in which the adequate amount of flash is obtained based on the overall brightness of the obtained image has been commonly used. Recently, however, a flash adjustment method in which face detection is performed on the obtained image, and emission amount of the flash is controlled according to existence or nonexistence of a face, or the proportion of the detected face in the image.
For example, U.S. Patent Application Publication No. 20030071908 describes a method in which emission amount of a flash is reduced if a face is detected and the ratio of the face in the image is greater than or equal to a predetermined value. Further, U.S. Patent Application Publication No. 20060044422 describes a method in which emission amount of flash is obtained using only the image data of a region corresponding to a face in the image, or using image data in which a region corresponding to a face in the image is weighted greater than for the other regions.
The methods described in U.S. Patent Application Publication Nos. 20030071908 and 20060044422 may obtain an image of appropriate brightness without halation in the face portion or without the face portion becoming too dark, if a human face included in the subject is detected successfully. If, however, a human face included in the subject is not detected successfully, or a determination is made erroneously that a human face is included in the subject, the emission amount of the flash in flash photography becomes inadequate and an image of appropriate brightness is not obtained. Further, even when the face detection is successfully performed, if the subject in flash photography differs from the subject when the face detection was performed, the emission amount of the flash in the flash photography becomes inadequate.